Signaling system



July 2,1, 1931. l W, L EDISON 1,815,055

SIGNALING SYSTEM Filed Dec. 18, 1929 /M/fA/ra@ Patented July 21, 1931 parar; oFricE;

DELAWARE, ASSIGNOR TKOl THE W. L.

PORATION OF DELAWARE SEG-MARN@ SYSTEM Application filed December 1S, 1929. Serial No. 414,919.

This invention relates to a high frequency alternating current system and more particularly to means for interconnecting the tubes of an amplifying system. The system herein disclosed is particularly applicable to the amplification of radio signals, the interconnecting means being applied to the radio and/ or audio amplification stages, preventing oscillation due to mutual reaction in the former, and producing undistorted and efiicient amplification in the latter.

It is the object of the present invention to provide an interconnecting means for the tubes of an amplifying system, and a circuit including such means which produces a high degree of ampliiication without oscillation, distortion or losses involved in resistance suppression methods heretofore occurring in the n, radio frequency amplication stages and without distortion in the audio frequency amplification stages. The interconnecting means specifically consists of a novel element, the construction of which will be clear from the following description read in conjunction with the accompanying drawings,

in which:

F ig. 1 is a diagrammatic illustration of a portion of a circuit lembodying the improved y amplifying system; and

F ig. 2 is a View partly in section through the improved rtube interconnecting means. g

The improved tube interconnecting means is somewhat similar to that disclosed in my application Serial No. 305,272, filed Septembei' 11, 1928, patented March 18, 1930, No.

1,750,954, in that it includes a body of liquid in the field of a coil and having an electrode contacting with the liquid. The present interconnecting means however, utilizes only one coil wound thereon and is illustrated in Fig. 2 vas having only one coil.l It will be understood, of course, that the transformer illustrated in my prior application may be used, the secondary coil, only, being connected in the circuit while the primary coil remains idle; or if desired, the two coils might be connected in series to form one coil. In Fig. 2, the interconnecting means is referred to generally T, and consists of a base 2 Von which is mounted a cylindrical cup 4 of insulating material and having a top opening` in which is threaded a cap 6 of insulating material. Suitably supported, as by a. metallic bolt or rod extending through cap G, is a metallic electrode 10, o f copper for example, which is submerged in a suitable liquid 12 contained in cup 4. The upper end of rod 8 is provided with a soldering lug 14 to which connection may be made.

lsvound on the outside of the cup or cell 4 is a coil S which will be hereafter referred to as secondary coil by reason of the fact that it is analogous to the secondary coil of an ordinary inter-tube transformer. Vhile this coil is mounted directly on the cell, it may be otherwise mounted as long as the liquid in the cell iswi'thin its field. The number of turns, shape of the cell, ete. are determined by the circuit or portion thereof in which the cell is used. For example, where used in the radio frequency amplification stages, there are relatively few turns whereas in the audio frequency stage there are many turns of fine wire.

The liquid within the cell, similarly to that used in theccell described in my application for signaling system, Serial N o. 288,563, filed June 27, 1928, may be of various types although water or an electrolyte solution is preferred. If it is desired to positively prevent spilling, the solution may be gelatinized as described in my prior application.

ln one 'preferred form of the circuit illustrated in Fig. 1, there are three radio frequency amplification stages using screen grid tubes, adetector, and two audio frequency amplification stages, the last audio stage being of the pusli-pull type.

In this circuit, the tubes V1, V2, and V3 are in the radio frequency amplification stages, and tubes V5 and V6 and V6 are in the audio frequency amplification stages. Tube V, is the detector. These tubes may be of any of` the well known types for the specific purposes having either filament or heater eathodes heated by either direct or alternating current. The tubes in the radio frequency amplification stages are shown as of the screen grid type although the ordinary three element "tubes may be used if desired.

i ranged The plate voltage supply is conventionally indicated as a battery B. Preferably, however, a B-eliminator or other direct current source is used. Suitable negative biases are obtained for the grids by the interposition of resistances between the cathodes and the negative side of the plate supply. The potentials of the screen grids may be regulated through a battery K and potentiometer P aras illustrated. rlhis constitutes the ordinary method of volume control by a screen grid.

Referring specifically to the circuit, a resistance or inductance R is connected to the electrode of the first cell and the ground at its ends and to the aerial at a variable intermediate point, although the incoming signals may be otherwise impressed upon the electrode. The coil Sl of the cell and the variable condenser C1 form a parallel resonant circuit joined at. one end to the grid of tube V1 and at the other end to the ground.

The plate of tube V, is in turn connected to the electrode of cell T2, the coil S2 of which and condenser C2 form a second resonant circuit the potential of which is impressed between the grid of tube V2 and the ground. Similar intertube connections including T3, S3, C?, and T4, Sl, C4 in turn join tubes V3 and V., in the cascade. Condensers G1, C2, (31 and (lL are mounted in a gang on a common shaft so that the resonant circuits may be simultaneously tuned in the usual manner.

rEhe tube il., which is the detector, may be operated with or without a grid condenser and grid leali. The plate of this tube is connected through a radio frequency choke coil l with the electrode of cell T5, a by-pass condenser joining the plate and ground. As contrasted with cells T1, T2, T3 and TA1 which have relatively few turns wound thereon, the coil S on cell T5 has a large number of turns of line wire similarly to the secondary of the ordinary audio-frequency transformer correspondingly used. This coil is connected between the grid of tube V5 and the ground.

The plate of tube V5 is connected to the electrodes of the symmetrically arranged cells TG and TG, the coils SG and SG thereon having many turns, being joined at corresponding ends and the junction being grounded through a resistance. 'he other ends are connected to the grids of tubes V6 and VG. the plates of which are connected to the loud speaker terminals Ll as illustrated. l.Vhile the plate supply B is shown as furnishing the plate currents for tubes V6 and VG', it is generally desirable to have a considerably greater voltage applied to these output tubes, than to the other tubes.

While there has been described a circuit which operates very satisfactorily, it will be clear that the intertube connecting means forming the subject matter of the invention is of quite general application. There may be different numbers of radio and/or audio amplification stages; or the cells may be used only in the radio or only in the audio stages. The present arrangement may also be used in combination with the arrangements shown in my prior applications Serial Nos. 288,563 and 305,272, referred to above.

When t ie intertube connecting means such as described is used in one or more of the amplification stages, it is found that oscillation is effectively prevented and sharper selection and higher degrees of amplification are attained. At the same time the amplification is practically uniform at low as well as high frequencies.

lt will be noted that there is no interposition of any resistance, potentiometer, or the like, in the grid or plate circuits except, of course, the relatively low grid biasing resistances. That is, no stabilizing resistances are needed. Consequently there. is no diminution of amplification which ordinarily results from the usual methods for suppressing oscillation. Also, as compared with so-called neutralized or balanced circuits for suppression of oscillation in which rery small condensers are used to balance capacities of the tubes, changes of tubes in circuits embodying the present invention do not necessitate readjustmentof the circuit to prevent oscillation.

The action of the circuit described is not clearly understood, and hence no explanation is attempted.

rlhe present application includes claims generic to the circuit shown in this application and that shown in my prior application, Serial No. 305,272, above referred to.

lhat I claim and desire to protect by Letters Patent is:

l. An amplifying system including a thermionic tube having cathode, grid and plate elements, a grid circuit joining the grid and cathode of the tube, a coil in the grid circuit, and a cell including a body of liquid, said body of liquid being in the field of the coil.

2. An amplifying system including a thermionic tube having cathode, grid and plate elements, a grid circuit joining the grid and cathode of the tube, a coil in the grid circuit, and a. cell including a body of liquid and an electrode contacting therewith, said body of liquid being in the field of the coil, and the electrode being connected to a point the potential of which varies during the operation of the system.

3. An amplifying system including a thermionic tube having cathode, grid and plate elements, a grid circuit joining the grid and cathode of the tube, a coil in the grid circuit, a cell including a body of liquid within the field of the coil, and an electrode contacting with the liquid, said electrode l`circuit being connected to a point of varying potential extraneous to the grid circuit.

fl. An amplifying system including a thermionic tube having cathode, grid and plate elements, a tuned grid circuit joining the grid and cathode of the tube and including a coil and condenser, a cell including a body of liquid within the field of the coil, and an electrode contacting with the liquid, said electrode being connected to a point of varying potential extraneous to the grid circuit.

5. An amplifying system including a thermionic tube having cathode, grid and plate elements, a grid circuit joining the grid and cathode of the tube, a coil, variations iu voltage in which produce corresponding variations in grid potential, and a cell including a body of liquid, said body of liquid being in the field of the coil.

6. An an'ipli'fying system including a thermionic tube having cathode, grid and plate elements, a grid circuit joining theV grid and cathode of the tube, a coil, variations in voltage in which produce corresponding variations in grid potential, and a cell including a body of liquid and an electrode contacting therewith, said body of liquid being in the field of the coil, and the electrode being connected to a point the potential of which varies during the operation of the system.

7. An amplifying system including a thermionic tube having cathode, grid and plate elements, a grid circuit joining the grid and cathode of the tube, a coil, variations in voltage in which produce corresponding variations in grid potential, and a cell including a body of liquid and an electrode contacting therewith, said body of liquid being in the field of the coil, and the electrode being connected to a point of varying potential extraneous to the grid circuit.

S. An amplifying system including a plurality of thermionic tubes each of which has cathode, grid and pl ate elements, a plate circuit joining the plate and cathode of one tube, a grid circuit joining the grid and cathode of a succeeding tube, a coil in said grid circuit and a cell including a body of liquid and an electrode contacting therewith, said body of liquid being in the field of the coil, and the electrode being connected to the plate circuit.

il. in amplifying system including a plurality of thermionic tubes each of which has cathode, grid and plate elements, a plate circuit joining the plate and cathode of one tube, a grid circuit joining the grid and cathode of a succeeding tube, a coil in said grid and a cell including body of liquid and an electrode cont-acting therewith, said body of liquid being in the field of the coil, and the electrode being connected to the plate of the precedingL tube so as to be at substantially the same potential as the plate. l0. An amplifying system including a plurality of thermionic 'tubes each of which has cathode, ygrid and plate elements, a plate circuit joi-ning the plate and cathode of one tube, .a grid circuit joining the grid and cathode of a succeeding tube, a coil in said grid circuit and a cell including a body of -liqufid and an electrode contacting therewith, said body of liquid being in the field of the coil, andthe electrode being connected so that variations in potential are produced therein corresponding to variations in poe tential of the .plate of the preceding tube.

ll. An amplifying system includingv a plurality of thermionic tubes each of which has cathode,'grid and plate elements, a plate circuit joining the plate and cathode of one tube, a grid circuit joining the grid and cathode of a succeeding tube, `.a coil, rvariations in voltage in which produce corresponding variations in the potential of the grid of said succeeding tube, and a cell in` cluding a body of liquid and an electrode ccJitactingv therewith, said body of liquid l in the field .of said coil, and the electrode being connected so that vvariations in potential are produced therein corresponding to variations in potential of the plate of the n'ecedin g tube.

l2. An amplifying system including a plurality of thermionic tubes each .of which hasA cathode, grid and plate elements, a plate circuit joining the plate and `cathode of one tube, a. grid circuit joining the grid and cathode of a succeeding tube, a coil, variations in voltage in which produce corresponding variations in the potential of the grid of said succeeding tube, and a. cell including a bodj7 of liquid and an electrode contacting therewith, said body of liquid being in the field of said coil, and the electrode being connected to said plate circuit.

i3. An amplifying system including a plurality of thermionic tubeseach of which has cathode, grid and plate elements, a plate circuit joining the plate and cathode of one tube, a grid circuit oining the grid and catl ode of a succeeding tube, a. coil, variations in voltage in which produce corresponding variations in the potential of the grid of said succeeding tube, and a cell including a body of liquid and an electrode contacting therewith, said body of liquid being in the field of said coil, and the electrode being connected to said plate of the preceding tube so as to be at substantially the same potential as the plate.

14. A high frequency receiving system including a thermionic tube having cathode, grid and plate elements, a grid circuit joining the grid and cathode of the tube, a coil in the grid circuit, a cell including a body of liquid, said body of liquid being in the field Cil of the coil, an electrode contacting with the body of liquid, and an antenna having electrical connection With the electrode.

15. A high frequency receiving system including a therinionic tube having cathode, grid and plate elements, a grid circuit joining the grid and cathode of the tube, a coil and variable capacity in parallel in the grid circuit, a cell including a body of liquid, said body of liquid being in the iield of the coil, an electrode contacting with the body of liquid, and an antenna having electrical connection with the electrode.

16. A high frequency receiving system including a thermionic tube having cathode, grid and plate elements, a grid circuit join ing the grid and cathode of the tube, a coil, variations in voltage in which produce corresponding variations in grid potential, a cell including a body of liquid, said body of liquid being in the field of the coil, and a variable capacity shunted across the coil.

17. A. high frequency receiving system including a therniionic tube having cathode, grid and plate elements, a grid circuit join ing the grid and cathode of the tube, a coil, variations in voltage in which produce corresponding variations in grid potential, and a cell including a body of liquid, said body of liquid being in the field of the coil and being in an input circuit.

In testimony of which invention, I have hereunto set my hand, at Vxilrnington, Delaware, on this 16th day of December, 1923.

VILLIAM LESLIE EDISON. 

